1. Field of the Invention
This invention relates generally to the controlled use of television receivers and particularly to parental control of the use of television receivers and associated equipment such as cable boxes.
2. Description of the Related Art
Parental control is presently available in some television receivers, video cassette recorders, and cable boxes on a limited basis. In these devices, certain channels may be locked out. However, the locking out of channels does not prevent children from spending excessive time watching television instead of studying or doing other things. Other devices limit the amount of time, but do not provide for selective viewing to prevent viewing of undesirable programs. One example of parental control at the television receiver is disclosed in U.S. Pat. No. 4,510,623 to Bonneau et al. A local oscillator for electronically tuning the television is controlled by a phase lock loop which is responsive to the output signal from a microprocessor. The microprocessor provides the output signal only if the selected channel has not been inhibited. To inhibit a channel for a period of time, the user enters a lockout code which is stored in a non-volatile memory. The memory provides one input to the microprocessor which is compared to the input by a user selecting a channel to be viewed. The microprocessor determines whether the selected channel is one of the inhibited channels and, if it is, does not generate the necessary signal for tuning to that channel.
Another prior art patent that discloses the blocking out of selected channels is U.S. Pat. No. 4,718,107 to John J. Hayes. The parental control disclosed in the Hayes patent is provided in a converter box. In this system, if the access code is forgotten, the converter box has to be taken to the business office of the CATV system to have the memory purged of the blocked-out channel information and the access code, and a new access code must be entered. In the Hayes device, only selected channels can be clocked which does not allow the selected blocking of particular programs in a channel.
In general, the present state of the art concerning parental control suffers from a number of drawbacks. In particular, the control is very limited and does not provide a parent the broad control desirable for controlling the viewing or use of a television by a child.
Some cable channels are scrambled and must be decoded by a cable box before being sent to a television tuned to channel 3 or channel 4. In this case, controlling the tuning of the television is ineffective, because the television is always tuned to channel 3 or 4. Even if a particular channel is blocked in the cable box or converter box, this does not provide the parent selective control over programs within a channel.
Accordingly, there is a need in the art for apparatus and methods for improved parental control of television use to provide a parent broad control for both blocking unacceptable programs and/or selecting acceptable programs that are available for viewing. There is also a need in the art for improved parental control of multiple televisions attached to a common signal source.